Machine for grinding toothed gears



July 15, 1947. A. RICKENMANN MACHINE FOR GRINDING TOOTHED. GEARS .Filed Aug. 24, 1945 8 Sheets-Sheet 1 lrilhl bill Filed Aug. 24, 1945 8 Sheets-Sheet 2 S N E July 15, 1947. A. RICKENMANN MACHINE FOR GRINDING TOOTHED GEARS Filed Aug. 24, 1945 8 Sheets-Sheet 1 V ltlllllllr/lll I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I l I I I I I I I I I I I I I I I I I I I I I I I I I I n July 15, 1947. A. RICKENMANN 2,424,191

MACHINE FOR GRINDING TOOTHED GEARS I Filed Au 24, 1945 s Sheets-Sheet 4 y 15, 1947- A. RICKENMANN 2,424,191

MACHINE FOR GRINDING TOOTHED GEARS Filed Aug. 24, 1945 8 Sheets-Sheet 5 WWW July 15, 1.947. A. RICKENMANN 2,424,191

MACHINE Fog GRINDING Too'rmn GEARS Filed Aug. 24, 1945 8 Sheets-Sheet 6 July 15, 1947. A/RICKENMANN MACHINE FOR GRINDING TOOTHED GEARS Filed Aug. 24, 1945 8 Sheets-Sheet 7 Fig. 7a

July 15, 1947.

-A. RICKENMANN 2,424,191

MACHINE FOR GRINDING TOOTHED GEARS Filed Aug. 24, 1945 8 Sheets-Sheet 8.

fi fig/3 15 @u ///////////////fi Patented July 15, 1947 MACHINE FOR GRINDING TOOTBED GEARS Alfred Rlckenma'nn, Kusnacht, Zurich,

' Switzerland Application August 24, 1945, Serial No. 612,341 In Switzerland March 10, 1945 12 Claims. 1

The present invention relates to a new and improved machine for grinding the teeth of spur gears and of spiral gears by means of a grinding hob. The invention more especially relates .to machines of the said type having a separate electric synchronous motor for driving the grinding hob and one for the shaft carrying the gear, the teeth of which are to be shaped.

It is to be understood, however, that the present disclosure is by way of illustration and it is not restrictive of the invention, it being obvious that the invention is susceptible of various modifications and embodiments, certain novel features may be employed in other relations than herein disclosed and the terms here used are merely terms of description and not terms of limitation.

The general aim of the invention is to provide an improved machine by means of which spur wheels or spirally toothed gears may be ground expeditiously and economically and with the greatest precision.

More particularly, the aim of the invention is to provide an improved machine by means of which the said toothed gears may be ground with extreme accuracy and at a high rate of production.

A further aim of the invention is to provide an improved machine having various features of novelty and advantage and which is characterized by its relative simplicity, by the smoothness and lack of vibrations or other disturbing factors with which the various movements are brought about, by the facility with which the machine may be set up; and the manner in which it is controlled to bring about the various movements in the proper sequence and relation.

Other objects will be in part obvious and in part pointed out more in detail hereinafter.

The invention accordingly consists in the features of construction, combination of elements and arrangements of parts which will be exemplified in the construction hereinafter set forth.

In the accompanying drawings an embodiment of the invention is shown by way of an example in a diagrammatical manner:

Fig. 1 is a side elevation of the machine.

Fig. 2 is a longitudinal section through the workpiece-driving gear of the machine and through the means to feed the carriage, carrying the grinding tool.

Fig. 3 is a side elevation, the automatic in-feeding device for the grinding tool carriage being shown in section.

Fig. 4 i a section taken on line A-A of Fig. 1, the workpiece carriage being shown in its inoperative position.

Fig. 5 shows in a diagrammatically sectional view the hydraulically and the manually operable feeding device for the grinding tool carriage.

Figs. 6, 7 and 7a show each diagrammatically 2 the hydraulically and electrically controlled devices for reversing the movement of the workpiece carriage.

Figs. 8, 9 and 10 show the position of members controlled by the workpiece carriage while the carriage is moving.

Figs. 11 and 12 show the position of the same member during the reversing at the upper end position of the carriage.

Figs. 13 and 14 show the positions of said members during the reversal of the carriage at its lower end.

Fig, 15 is a longitudinal section of the controlling device.

Fig. 16 illustrates a detail of the reversing device for the workpiece-carriage.

Figs, 17 and 18 show the developed faces of two different spirally toothed gears.

Fig. 19 is a cross-section .through the automatic working in-feed mechanism for the grinding wheel carriage.

This machine in general comprises means for supporting a toothed wheel, means for supporting and driving a grinding wheel in operative relation to the toothed gear, means for efiecting a traverse movement axially of the toothed wheel and the grinding wheel, means to rotate said toothed wheel while traversing the grinding disk, and means for effecting a relative movement between the toothed wheel and the grinding wheel. The machine is also provided with a truing device for the operative face of the grinding disk and means for actuating the truing device in such a manner that the contour of the working faces of the ridge on the grinding wheel is maintained correct and so that the teeth of a spur wheel or a spirally toothed wheel may be ground to correct finished size.

On the base I of the machine a slide 2 (Figs. 1, 2, 3) is mounted to be movable in a horizontal guide way and carrying an electric synchronous motor 3 (Fig. 3). The armature shaft of the motor 3 is clutched to the shaft 6 of an abrasive grinding wheel I, said shaft 6 running in bearings 4, 5. The cylindrical working face of the wheel I is profiled to grind the pre-proflled teeth of toothed gears.

On the base I a, support 8 (Figs. 1 to4) isfastened carrying a drum 9 (Figs. 2, 4). The drum 9 is rotatably mounted in said support 8 and is provided with means to assist the drive of the workpiece i2. A slide I0 running in guide ways on the front face of the drum 9 carries a headstock and a tail-stock I l and therewith the'workpiece l2.

To grind obliquely toothed gears means are provided to fasten the workpiece I! at the proper angular position'with reference to the grinding wheel I. The drum 9 with the slide ill for the workpiece thereon may be adjusted to the desired angular position by means of a hand wheel i3 (Figs. 3, 4) fixed to a shaft l4 operating aworm wheel and worm l5, IS. A scale I! (Fig. 1) marked on the drum 9 facilitates the exact adjustment of the grinding wheel and the gear blank with reference to each other. By means of two screw bolts l3, I9 (F ig. 4) the drum 9 is adapted to be locked to the support 3 in the proper working position.

A special feature of the machine according to this invention consists therein that the least possible number of elements is arranged between the synchronous motor 23 (Fig. 2) and the shaft 32 employed for driving the workpiece l2. Moreover, only spur gears are used as transmission members between the motor and the workpiece driving spindle.

In machines of known construction worm gears in combination with bevel gears are commonly used for said purpose, but these known gears do not produce the same accuracy in grinding that can be attained with spur wheel gearings.

For this reason the motor 23 for driving the workpiece l2 and connected to the drum 9 drives by means of a. shaft 2i (Fig. 2) the spur wheels 22, 23, 24, 25 and by the change speed gears A, B, C, D a long spur wheel 33. The rotations of the latter are transmitted to a gear 3i fixed to a shaft 32 and the latter drives by means of the spur wheels 33', 34, the working spindle 35. On a spindle 33 mounted between the centers 36, 31 one or several workpieces i2 are fastened. By a dog 39 the rotations of the spindle 35 are transmitted to the workpiece carrying spindle 38.

The change speed gears A, B, C, D are brought in operation according to the number Z of teeth of the workpiece l2. The casing 43 and the four spur wheels 22, 23, 24, 25 mounted therein form a differential gearing. For grinding spur gears with straight teeth, the casing 43 will be arrested during the grinding operation by means described later on. As the number of rotations of the workpiece 12 has to be lower than those of the shaft of motor 23, the said gears 22, 23, 24, 25 act also eration. This may be effected in the following manner:

To the slide l3 carrying the workpiece i2 a rack 45 (Figs. 1, 4) is fastened, with which a pinion 45 is in engagement.

While the slide i3 is movin in its guide way the pinion 45 drives by means of the shaft 41 (Figs. 6, 7, 7a) and the four change speed gears E, F, G, H the shaft 52 and by a pair of bevel gears 53, 54 a shaft 55 and a spur wheel 55 a toothed rim 43l of the casing 43 of the difl'erential gearing which casing is now caused to rotate. By rotating the casing 43, a differential drive of the workpiece I2 is attained.

The number Z of the teeth of the workpiece i2 to be ground will determine the use of either of the change speed gears A, B, C, D. The rate of transmission between the motor 23 and the workpiece i2 is determined by said gears. From this rate of transmission together with the desired pitch of the teeth to be ground the size of the four change speed gears E, F, G, H determining the differential motion are calculated.

A right hand pitched workpiece would have to receive an additional turning movement in the same direction in which the workpiece-shaft rotates. A left hand pitched workpiece would have to receive an additional movement in the opposite direction to the direction of rotation of the workpiece-shaft. Left hand screw gears are produced by inserting an additional change speed gear E, F, G or H in the differential gear train.

The transmission of the turns of the shaft of motor 23"onto the working spindle 35 is effected by the motor 23 which drives the diiferential gear-change speed gears 22-25. For grinding a spirally toothed workpiece having for instance a number of teeth equal to Z1, a pitch angle or, an angular pitch X and a circular pitch ts, the driving gear train would have to include the change speed gears A1, B1, C1, E1, F1, G and H.

By the means described it is possible to adjust the machine for working on gears having different numbers of teeth Z2, Z3, Z4, etc., but of the same angle a and of the same circular pitch as by simply changing the change speed gears A, B, C and D according to the number of teeth of the gear to be worked while the change speed gears E, F. G and H may remain in the train of gears.

.Pairs of spirally toothed gears of the highest precision may be produced as the teeth are shaped always with the same diflerentiai train of gears E, F, G and H by which exactly the same lead angle or is produced.

In the Figures 17, 18 two spur wheels are shown having the same lead angle a and the same circular pitch ts. The spur wheel shown in Fig. 17 has Z1 teeth and a lead of the spiral equal to X. The spur wheel in Fig. 18 has Z: teeth and a lead of the spiral equal to Y. From this follows:

The lead of the spiral changes by a given lead angle a in proportion to the number of teeth. The ratio zizzz may be given by the ratio of the two sets of change speed gears.

From this formulae follows: that with a set of gears A3. C2 B2. D2

for grinding the teeth of a wheel with a number of teeth equal to Z: a differential motion for a spiral lead Y may be obtained without replacing the train of gears E, F, G and H used for grinding a toothed gear with a number of teeth equal to Z1 and a spiral lead X.

To feed the carriage l3 and to operate the dif-, ferent auxiliary controlling devices of the machine described hereinafter, fluid pressure operated devices and electrically controlled means are provided (Figs. 1, 6, 7, 7a). The fluid under pressure is delivered by a pump 523 which is connected by the pipes 533, 543 and 553 to the controlling device 553. By this device 533 the movements of the different controlling means are initiated. Electric current is supplied by the net 513, 583.

The pressure of the liquid is controlled by an pipe 558 to the main valve 8| and passes on to the different controlling valves 12, I38 as described hereinafter.

when working, the slide I8 is moved upwardly and the workpiece I2, while being rotated, is passed along the rotating grinding wheel 1. The latter will be drawn back from its working position while the slide I8 moves downwardly by means described hereinafter. The stroke of the slide I8 is limited by adjustabiy mounted stops 84, 85 (Figs. 6, '1. 7a).

While the slide I8 performs its upward stroke, the main valve 8| is in the position shown in Fig. 6. Liquid under pressure from pipe 558 enters the circular groove 88 and the bore 88 which communicates with an annular groove 18 connected with a passage 1| leading to the piston valve 12. To operate the piston of valve 12 a rack 12I is provided on the piston rod with which a gear 15 is in mesh. The gear 15 is keyed to a shaft 14 which may be rotatably adjusted by a hand lever 13 into three different positions (Figs. 6. 7, 7a).

In the position marked Fast (Fig. 7a) in which the lever 13 is directed to the right and upwardly, the device is prepared for work. The piston valve 12 has opened the passage for the liquid under pressure to flow through annular groove I22 into the tubes I8, 11 and into a bore 18 in the piston rod 8| and into the cylinder 18 arranged at the upper end of slide I8. The cylinder 18 moves upwardly together with the slide I8, while the latter performs its stroke, until lower end of the piston rod 8| abuts on the support 88 of drum 8. The influx of a great quantity of liquid under pressure produces a quick upward movement of the slide I8.

To make the machine ready for the grinding operations the lever 13 is brought into its vertical position denoted by Slow" (Fig. 6). The

valve 12 is set thereby to pass the pressure fluid from annular groove 122 and tube 82 to a pump 83 the fluid flowing through the passages 11, 18 into the cylinder 18.

The movement of the slide I8 is eifected now by the pump 83 arranged between the conduits TI, 82.

The pump 83 is provided with means known per se to control the amount of liquid discharged. The pump 88 is driven by a spur wheel 84 engaging the long spur wheel 88. It is a special feature of this device that the drive of the pump 83 is made dependent on the ratio of transmission of the set of gears A, B, C and D. The feed for each full turn of the workpiece I2 may be seen from the position of the controlling device ofpump 83.

By turning a knob 85 (Fig. 1) a cam 81 is adjusted by means of a shaft 88 rotatably mounted in the drum 8, the volume of pressure liquid is controlled thereby. The feed of the slide I8 for each full turn of the workpiece I2 may be adjusted within certain limits by, said means.

By placing the lever 13 in its position denoted by Stop the slide I8 is stopped at any position of its stroke. The piston valve 12 closes the passages 18, 82 of the pressure liquid.

To change the direction of the travel of the slide I8 the following means are used:

Near the guide-way for the slide I8 a small casing 88 (Fig. 1) is arranged in which a shaft 8| (Fig. 15) is journalled on which a short lever 88 (Figs. 6, 7, 7a, 10, 12, 14, 15) is fastened. The shaft 8| is provided with two recesses 82 (FIB. 8) on which are acting two springs 88. The springs 6 83 are of equal force, they abut on the wall of the casing 88 and have the tendency to keep the lever 88 in its horizontal position.

On a flattened part at the end 8 (Figs. 9, 11, 13, of the shaft 8| one end of a flexible band 84 is fastened the other end of which is attached to the wall of casing 88. The flexible band 84 runs parallel to the plane 8I2 of the end 8 of shaft 8| as long as lever 88 is in its horizontal position.

When the slide I8 moves upwardly, the dog 84 (Figs. 1, 12) comes to bear on the lever 88. The

latter and with it the shaft 8| is rotated in the direction of the hand of the clock. The plane 812 assumes an oblique position and the edge 8|8 (Fig. 11) bends the band 94 sufficiently to press a contacting part 84| (Fig. 11) against the switch button (Figs. 6, 7, 7a) of an impulse switch 88 of known construction. The reversing of the slide I I8 is thereby initiated.

In a similar manner the lever 88 will be moved in the anticlock direction by the dog 85 (Fig. 14) when the slide I8 moves downwardly. The flexible band 84 will again be stressed and contact is made at 84I with the button 85.

To reverse the travel of the slide l8 at any point between the ends of its stroke and without making use of the switch 88 and the dogs 84, 85 a push button 88 (Figs. 1, 6, 7, 7a) is provided on the plate 81 mounted on the base I.

The said means to reverse the travel of the slide I8 either by hand or automatically by the dogs 84, 85 comprise a device to direct the given electric impulses in proper sequence on to the controlling magnets 81, 88 (Figs. 1, 6, 7, 7a) in such a manner that the upstroke of slide I8 is a working stroke and the downstroke an idle stroke. To attain this, a switching device I88 (Figs. 6, 7, 7a, 16) is arranged, actuated by the shaft 41 and gear 48. The said shaft 41 is driven by the gears E, F, G, H and the gearing 52 to 58 from the casing 48 of the differential gearing.

In a sleeve I88a (Fig. 16) of said switching device, a contact pin |8| (Fig. 16) is arranged, and a radial spring I82 in said sleeve |88a urges a friction member I83 against the shaft 41. The portion I8I| of the contacting pin I8| projecting radially from the sleeve I88a is arranged between two circuit controlling devices I84, I85 arranged within the drum 8. The force of the spring I82 and the friction created by member =I88 is slimcient to turn the sleeve I88a by the shaft 41 as long as the projecting end I8II of the contacting pin |8| does not abut on either of two buttons I84l, I85I of said devices I84, I85.

As diagrammatically shown in Figs. 6 and 'la, the contacting pin I8II presses on the button |84| of the switch I84 while the slide I8 moves upwardly. From the diagram in Figs. 6, 7, and In it will be seen that the next impulse-whether given manually by operating push button 88, or automatically. by dog 64will operate the reversing magnet 88- if a switch I15 is closed.

When the slide I8 changes the direction of its travel, there changes too the direction in which the shaft 41 is turned. At the start of the return stroke of the slide I8 the sleeve I88a of the switching device I88 will take part of the rotation of shaft 41 and will be moved by an angle 6 (Fig. 16) anti-clockwise. The switch I85 is opened when the switch I84 is closed by the pin I8 and, the switch I85 when operated by the pin I8II closes the circuit of the magnet 81 controlling the working stroke. At the first current impulse the working stroke will be started. While these switching 7 operations are being performed the switch aI'I5 is kept closed for a purpose explained later on.

When the reversing magnet 99 (Figs. 6, 7, 7a) destined to control the return stroke of slide I is energized, it will attract the double armed lever 55 and turn the same. At the same time the link I connected to lever 55 moves the piston of the main valve 5| to the left into the position shown in Fig. 6. The piston stops the flow of the liquid under pressure to the diiferent controlling devices by closing the supply conduit 550.

By placing the lever I3 into the position Slow or "Fast the slide I0 will move downwardly pressing the liquid into the collecting basin through the passages I8, 11, I5, the annular groove I23 or I22, the passage I01, the annular All the elements used for the drive of the worki piece I2, viz. 44, 30-35, 20-23, 4|, 24, 25, 42, A, B, C and D are moving continuously in the same direction whether the slide I0 moves upwardly or downwardly.

The elements, however, which form part of the differential gearing, used for the grinding of obliquely toothed gears, viz. 45-41, E, F, G and H, 52-40, 40 change their direction of movement to ether with the slide I0.

By changing the direction of movement of the members of the driving train 45-", E, F, G, H, 52-58, 40 the lost motion and the play may result in inaccuracies. By grinding gears with a high spiral pitch much time is lost during the reversal of the motion to take up all the play of the members of the train.

To obviate these drawbacks the following means are employed:

In a bore IIO (Fig. 1) of the support 0 a controlling piston III (Figs. 6, '7, 7a) is rotatably mounted. To the piston III a hand lever H2 is fastened by which the piston III 'may be set in either of two positions:

Spiral teeth or "straight teeth When the lever I I2 and therefore the piston III is in the position Spiral teeth" liquid under pressure passes from the pressure reducing valve 590 through the pipes H4, H5 (Fig. 6) piston valve III, through pipe II3 into a rotary motor 0 of known construction. The casing of motor II! is fastened to the drum 9. On a shaft III rotatably mounted in the drum 9, a rotor H0 and a spur wheel II9 are fastened. The spur wheel H9 is in mesh with a toothed rim 40I of the casing 40 of the differential gearing.

Owing to the eccentric position of the rotor III in the motor casing the liquid under pressure will produce a torque which will be transmitted from the shaft III to the spur wheel H9 and therefrom to the train of gears 40, 55 to 52, H, G, F, E, 41 and 40. By reversing the movements of the slide I0 the direction of rotation of the members of said train of gear will be reversed too. The torque is such that whatever the direction of the moving slide I0 is, the train of gear will move in the same direction. By reversing the motion of the slide I0, there will he therefore no dead play at all.

The ratio of transmission of the rack 45 and the toothed rim 40I corresponds to the spiral pitch of the workpiece and is determined by the gears E, F, G and H, It may vary within wide limits. By means of a pressure controlling valve I20 built into the pipe H5 and with the aid of a pressure gauge I21, the torque may be controlled in such a manner that the force acting on the rack 45 of the slide I0 can be adjusted to be approximately the same whatever the ratio of transmission E, F, G and H will be.

In the drum 9 a small casing I2I (Figs. 6, 7, 7a) is arranged having -a bore I23 in which the piston I22 is slidably arranged. The bore I23 is connected by a pipe I24 with the controlling valve III. When spirally toothed spur wheels are ground, a spring I25 presses the piston I22 to the right and forces the liquid in the bore I23 into a pipe I24 and through a passage IIII in the piston of valve III back into the basin.

When the lever H2 is brought into the position Straight teeth the liquid under pressure passes from the pressure side 530 of the pump 520 (Figs. 7, 7a) through a passage I I I2 of a valve and the pipe I24 into the cylinder I23. The piston I22 moves to the left until the outer end I22I of its piston rod comes to bear on the casing. The latter is now arrested and any differential motion is prevented.

To operate the grinding carriage 2 (Fig. 1, 2, 3) movable in the guide ways I25, I28 of the base I the following means are employed:

The screw threaded portion I29 (Figs. 2, 5) of the feeding spindle I30 engages a nut I3I on the support I32 of the carriage 2. A part of said spindle I30 between the ends thereof is provided with splines and extends axially through a conical gear I33 rotatably moimted in an arm I34 of the base I. The outer end I35 of the spindle I30 serves as a feeding piston and is slidably znounlted in a cylinder integrally formed with the ase By turning the hand wheel I36 (Fig, 1) a shaft I 31 rotatably mounted in the base I is turned and therewith the bevel gears I30 and I33, of which the latter is slidably keyed to the splined portion of spindle I30. The rotations thereof are transmitted to the feed spindle I30 and by it to the grinding disk carriage 2.

The device to move the carriage 2 by hand is constructed in such a manner that the latter may be adjusted manually independently from the hydraulic feeding mechanism.

The adjusting of the carriage 2 over a greater distance, say for changing the workpiece or for measuring purposes, is more conveniently eflected by the hydraulic feeding device as'follows:

At the controlling unit 560 a piston valve I39 (Figs 1, 6, 7, 7a) is arranged which is connected by conduits I40, I with the main governing valve 5|. To the piston of valve I39 a rack I39I is attached. The piston of valve I39 may be axially adjusted to three different positions by means of a hand lever I42, fixed to a shaft I43 and carilg'isnlg a spur wheel I44 meshing with the rack When the lever I42 is in the position Forward and when the main valve BI is in its operative position liquid under pressure passes through conduit I, through the annular groove I392, and into the pipe I45 and from there through the branch pipe I48 into the annular groove I41 01 the piston I35, through bore I40 into the cylinder I49 and pipe I50 into the annular groove I393 andconduit I40. The piston I35 and therewith the feed spindle I30 are moved to the right and the grinding disk on the carriage 2 i fed towards the workpiece I2.

As soon as the piston I35 has passed over a.

distance equal to K (Fig. 2) the edge I35I thereof starts to close the inflow-opening I46 and therewith the influx of liquid into the annular groove I41 of piston I35. At the same time the edge I352 (Figs. 2, 5) opens the narrow branch pipe I5I communicating with the pipe I46. By the small amount of liquid under pressure flowing through the pipe I5I into the cylinder I49, the latter is slowly filled and the carriage 2 is moved. The amount of liquid flowing into cylinder I49 and the speed of the feeding motion of carriage 2 may be controlled by means of a throttling valve I52 arranged in the pipe I5I.

On the end face I53I (Fig. 5) of a feeding spindle I53 arranged in the base I abuts the nose I54I of a double armed lever I54 rotatably mounted on a pin I55 of the base I. The other nose I542 serves as an abutment for the face I353 of the piston I 35 and limits its feeding motion. When feeding the carriage 2 towards the workpiece I2, a spring I51 is tensioned, abutting on said front face I353 and on the rib I56 of base I.

During the reversal of the motion of the slide I0, at the upper end of its stroke that is in advance of the downward stroke of the slide III, the grinding disk 1 will be automatically removed for a small distance from the workpiece I2. The slide I0 remains in this position until the governing device is again set to act for the next working period. This automatic withdrawing of the grinding disk 1 is eifected as follows:

The flow of the liquid to the cylinder I49 is stopped at once as oon as the main controlling valve 6I (Figs. 6, '1, 7a) has assumed the left hand end position shown in Fig. 7. in which the return motion of the slide I0 is effected. In this position of the main valve 6I the annular groove I59 communicates with the passage I40. When the valve 6| assumes the right hand end position the said groove I58 communicates with the outflow pipe I59 (Fig. 6). In its left hand end position the said groove I56 is filled with liquid from passage I40, the liquid being forwarded from the cylinder I49 owing to the expansion of the spring I51 acting on the face I353. The distance which the carriage 2 with the grinding disk I is automatically withdrawn from the workpiece I2 corresponds to the amount of pressure liquid which finds place in the annular groove I53.

By restarting the working stroke of the carriage 2 the liquid in the groove I58 is discharged through the pipe I59 (Fig. 6) into the basin. Liquid under pressure in the pipe I45 now feeds the carriage 2 towards the workpiece I2 until it abuts the nose I542 of the lever I54. The said withdrawingand infeed-movements are repeated at the beginning of each downward or upward stroke of the workpiece slide I0 as long as the main control valve 6| performs said movement too. and lever I42 remains in its Forward position.

In its middle position "Stop of the lever I42, the piston of valve I39 closes the passages I40, I at any position of the main control valve 6I. No liquid enters the pipes I45, I50 and the cylinder I49, nor leave the said parts. The carriage 2 remains now in the position it had attained at the moment of bringing the lever I42 to the position Stop."

When the lever I42 is brought to the position "Return the piston or the valve I39 is in its left 10 end position (Fig. 7a). The passage I, through which liquid passes at times is closed thereby.

The annular groove I393 connects the pipe I50 with the pipe I60 leading to the basin. The spring I51 acts on the piston I35 and the liquid in the cylinder I49 is forced into the pipe I50, the groove I393 and into the pipe I60. The carriage 2 moves backwardly into the hind end position in which the face I 352 of piston I35 rests against the wall I49I of the cylinder I 49.

The machine is provided with an automatic feeding device, comprising the pipes I6I, I62 and I63 which are connected to the main controlling valve 6|.

In the base I a right handed screw threaded feeding spindle I53 (Fig. 5) is arranged, the front face I53I of which serves as an abutment for the nose I54I of the double armed lever I54. On the spindle I53 a sprocket ear I64 (Fig. 3) is keyed having a long hub I64I. On the middle part thereof a toothed segment I65 is mounted while at the end portion I642 of the hub a ratchet gear I66 is fastened. The toothed segment I65 carries a pin I61 (Fig. 3) on which a pawl I60 is rockingly mounted, which pawl co-operates with the said ratchet gear I66. Only movements of the toothed segments I65 in counter-clock direction are transmitted to the ratchet wheel I66 and therewith to the spindle I53.

A chain I69 (Figs. 3, 19) passing over the sprocket gear I64 is fastened with one of its ends 'to a stud I10 on said gear and carries at its other end a weight I" which tends to rotate the ratchet gear I66 in the direction of the clock hand. The gear I66 is provided with a steering ledge I13 (Figs. 1, 5) carrying a contact I12. A stop pin I14 and a switch I15 are arranged on the base I (Figs. 1, 3).

The automatic feeding motion is effected as follows:

In a cylinder I8I of a support I16 (Figs. 1, 3, 5, 19) fastened to the base I a piston I11 is slidably arranged. Into an axial groove I11I (Figs. 3, 19) of the piston I11 projects a pin I18 fastened to the support I16. A spring I19 (Fig. 3) resting on the cover I16I (Figs. 1, 19) and guided in a bore I112 tends to press the piston I11 against the face I60I of a set screw I in the cover I162. The length of the stroke J of the piston I11 depends on the position of the set screw I30. The cylinder I9I is closed by the cover I162 and the space between the cover I162 and the piston face I113 communicates with the main controlling valve 6I by the pipes I63, I62 and I6I. Part of the mantle of the piston I 11 forms a rack I114 with which the toothed segment I65 is in mesh. If, after reversing at the end of a return stroke of the slide I0 the main controlling valve H has attained the right hand end position (Figs. 6, 7a) liquid under pressure passes through the annular groove 68 and the pipes I62, I 63 into the cylinder I8I and moves the piston I11 to the right (Fig. 19) until the same comes to rest on the cover I16I of the cylinder. The rack I114 turns the toothed segment I65 and the sprocket gear I64 in anti-clockwise direction. The pawl I69 transmits the said rotary movement on to the ratchet wheel I66 and therewith on to the spindle I53. The latter performs a turning motion equal to the angle 1 therewith, causing an axial displacement in the direction of the arrow (Fig. 5) according to the pitch of the screw threads on the spindle I53.

When lever I42 (Figs. 6, 7, 7a) is in the position "Forward" the carriage 2 is fed simultan- '11 eously by the moving of piston 6I until face I853 strikes against the double armed lever I54. During the grinding operation, pressure is kept up in the cylinder I48 and the displacement of the spindle I53 is positively transferred to the carriage 2 as an additional feeding motion.

By shifting the ratchet wheel I68 (Fig. 19) the weight I11 is lifted accordingly. On a shaft I82 (Figs. 1, 3) rotatably mounted in the wall of the base I, a hand lever I83 and a pawl I84 are fastened. A spring I81, fastened with one end in an eye I85 of the pawl I84 and with the other end to a stud I86 of the base I, keeps the pawl I84 in engagement with the ratchet wheel I66. Any motion of said wheel I66 in clockwise direction occasioned by the weight I1I is thereby obviated. 7

When the main controlling valve H is brought into the "Return stroke position the influx of liquid into cylinder I 8| (Fig. 19) is interrupted. By the action of the spring I18 the liquid in said cylinder I8I, in the pipes I63, I6I and in the annular groove 68 is driven through the outflow pipe I88 and the piston I11 is moved to the left until the latter is arrested by the face I88I. The toothed segment I65 and the pawl I68 are returned to their initial position, the pawl I68 riding over the teeth of the ratchet wheel I68 the latter being arrested by the pawl I84.

The said ratchet movements, by which the spindle I53 performs a. part rotation equal to Y are repeated until the stop I13 abuts on the stop I14 and until the contact I12 presses on the button I88 of the switch I15 (Figs. 6, '1, 7a).

The switch I15 is interposed between the switch I85 and the magnet 61 which controls the working stroke of slide I8. When the knob I88 is free of pressure th tongue I15I rests on the contact post I152 and forms a part of the circuit in which the magnet 61 is arranged. When the knob is depressed by the contact I12, (Fig. 1) the tongue .I15I (Figs. 6, 7, 7a) is moved until it is arrested by the contact post I153. A signal lamp I84 is now in the circuit in which the reversing organs for the slide I8 are arranged. The slide I8 is already moving in its last working stroke when the contact I12 (Fig. 1) is coming to make contact with the knob I88 of the switch I15. The reversing for the Return stroke is attained by the elements described in a known manner. At the end of the return stroke the slide I8 remains in its lower end position, all the other controlling elements for the feeding-in motion of the carriage 2 remain at rest in their back or rest position as the circuit through the working magnet 61 controlling the working stroke is interrupted owing to the position of the tongue I15I. By

closing the switch 86 while the slide I8 isin its lowermost position, the signal lamp I84 is lit but the magnet 61 is out of action.

In this position of the parts, measurements on the workpiece I2 may be made.

If the grinding is to be proceeded with, the carriage 2 is fed towards the workpiece I2 by the hand wheel I36 (Figs. 1, 5). By pressing the button I82 the open switch I15 is bridged over and the working stroke magnet 61 is energized. Liquid passed into the cylinder I48 and the grinding disk carriage 2 is fed in. In the cylinder I8I (Fig. 19) there is liquid under pressure but any motion of the piston I11 is impossible as the ledge I13 rests on the stud I14. The automatic infeed device has no effect on this additional working stroke.

The slide I8 performs an upward and. a co 12 secutive downward stroke. The switch I15 is not operated during this additional operation and the slide I8 remains at rest at its lowermost position which position is marked by the lightingup of the lamp I84.

When the grinding work has been finished the lever I42 is set into position "Return and the lever 13 (Figs. 6, '1, 7a) into the position "Stop. The slide I8 therefore remains at its lowermost position. The grinding disk carriage 2 is moved to its hind end position and the grinding motor 2 and the workpiece motor 28 are stopped by means not shown in the drawings. The workpiece I2 may now be removed from the machine and another one may be brought into position between the two centers 36 and 31. all the controlling elements into their initial positions the lever I83 (Fig. 1) is manually turned in a clockwise direction. The pawl I84 is lifted from the ratchet gear I66. Owing to the falling weight "I the gear I66 and therewith the spindle I53 is turned by the angle I to their initial positions, in which the face I13I abuts on stud I18 (Fig. 19) At the beginning of the return movement the knob I88 (Figs. 6, 7, 7a) of the switch I15 is set free. The tongue I15-I is returned automatically to the post I152 and the circuit through the signal lamp I84 is broken. After all the feeding elements have been returned to their initial position the lever I83 is released, thereby, the pawl I84 is again. pressed by the spring I81 in engagement with the ratchet gear I66 and the machine is now ready for another working operation.

To stop the machine, the piston of valve I38 (Figs. 6, 7, 7a) is set by means of the lever I42 to its Return position and after that the electrlc motors 3, 28 for performing the grinding work and for the workpiece carriage 8 respectively, are switched-off by pressing the button I83.

When switching off the motors 3, 28 while the piston of valve I38 is still in the Stop" or Forward position by pressing button I83, the workpiece I2 might be damaged as the two motors would not stop simultaneously. To prevent a wrong manipulation of the stopping means by the operator, the following device is provided.

On a support I88 (Figs. 1, 6, 7, 7a) fastened to the base I, an electromagnet I 88 is arranged. As long as the push button I83 rests on the posts I86, I81 the magnet I88 is energized and attracts the double armed lever I8I pivoted on said support I88. The right end I384 of the piston of the valve I 38 touches the arm I 8 while the valve I38 is in its "Forward position. When the switch controlled by the push button I83 is opened to stop the motors 3, 28 the circuit through magnet I88 is broken. A spring I85 arranged between the support I88 and the arm I 8 of lever I8I turns the latter in anti-clock direction. The piston of valve I38 is moved by the lever I8I into its Retum position and the carriage 2 moves to its outer end position.

The described means will also be eflective if by any means the current in the net 518, 588 fails and the force of the magnet I88 decreases. The workpiece I2 therefore will never be in contact with the grinding disk 1 when the motors 3, 20 are slowing down'to stop. The return movement of the carriage 2 is effected by mechanical means only.

As many changes could be made in the above construction and many apparently widely different embodiments of the invention could be made without departing from the scope thereof, it is To bring intended that all matter contained in the above description, or shown in the accompanying drawings, shall be interpreted as illustrative and not in a limiting sense.

It is also to be understood that the language used in the following claims is intended to cover all of the generic and specific features of the inscope of the invention which, as a matter of language, might be said to fall therebetween.

I claim as my invention:

1. In a gear grinding machine of the character described, a base, a slide provided with means tlh'ereon for rotatably supporting a toothed workpiece for a grinding operation, said means including a driven shaft carried by said slide in axial alinement with the workpiece when mounted on said slide and adapted to rotate said workpiece, a drum rotatably adjustably mounted on said base about a horizontal axis, a guide way on one end face of said drum in which said slide is mounted for reciprocative movement, a first synchronous motor secured to said drum and having its armature shaft arranged at right angles with respect to the axis of rotation of said drum, a train of spur gears between said armature shaft and said driven shaft carried by the slide, the axes of all of the spur gears in said train of gears being parallel to each other, a grinding wheel, a horizontal guideway on said base, a. slide on which said grinding wheel is mounted movable in said horizontal guideway toward and away from the end face of said drum on which said workpiece supporting slide is mounted, a second synchronous motor on said grinding wheel slid for operating the grinding wheel, and hydraulically operable means for adjusting the relative position of the grinding wheel slide with respect to the workpiece slide and for causing the workpiece slide to move in its guide way on said drum.

2. In a gear grinding machine of the character described, a base, a slide provided with means thereon for rotatably supporting a, toothed workpiece for a grinding operation, said means including a driven shaft carried by said slide in axial alinement with the workpiece when mounted on said slide, and adapted to rotate said workpiece, a drum rotatably adjustably mounted on said base about a horizontal axis, a guide way on one end face of said drum in which said slide is mounted for reciprocative movement, a first synchronous motor secured to said drum and having its armature shaft arranged at right angles with respect to the axis of rotation of said drum, a train of spur gears between said armature shaft and said driven shaft carried by the slide, the axes of all of the spur gears in said train of gears being parallel to each other, said trainof spur gears including a differential gearing, a casing for said differential gearing and forming a part thereof, said casing being mounted in said drum and rotatable about the axis of the .vention herein described and all statements of the armature shaft of said first synchronous motor,

said differential gearing reducing the speed of said armature shaft, gear means operated by the for operating the grinding wheel, and hydraulically operable means for adjusting the relative position of the grinding wheel slide with respect to the workpiece slide and for causing the workpiece slide to move in its guide way on said drum.

3. In a gear grinding machine of the character described, a base, a slide provided with means thereon for rotatably supporting a toothed workpiece for a grinding operation, said means including a driven shaft carried by said slide in axial alinement with the workpiece when mounted on said slide, and adapted to rotate said workpiece, a drum rotatably adjustably mounted on said base about a horizontal axis, a guide way onone end face of said drum in which said slide is mounted for reciprocative movement, a first synchronous motor secured to said drum and having its armature shaft arranged at right angles with respect to the axis of rotation of said drum, a train of spur gears between said armature shaft and said driven shaft carried by the slide, the axes of all of the spur gears in said train of gears being parallel to each other, said train of spur gears including a differential gearing, and a set of change speed gears arranged between said differential gearing and said driven shaft carried by the slide, a casing for said differential gearing and forming a part thereof, said casing being mounted in said drum and rotatable about the axis of the armature shaft of aid first synchronous motor, said differential gearing reducing the speed of said armature shaft, gear means operated by the workpiece slide when the same is moved in its guide way and operatively connected with said casing for rotating the same when grinding a workpiece having screw teeth, a grinding wheel, a horizontal guide way on said base, a slide on which said grinding wheel is mounted movable in said horizontal guide way toward and away from the end face of said drum on which said workpiece supporting slide is mounted, a second synchronous motor on said grinding wheel slide for operating the grinding wheel, and hydraulically operable means for adjusting the relative position of the grinding wheel slide with respect to the workpiece slide and for causing the workpiece slide to move in its guide way on said drum.

4. In a gear grinding machine as claimed in claim 3, including in said hydraulically operable means a hydraulic cylinder mounted on said workpiece slide, a pump for supplying pressure liquid to said hydraulic cylinder to cause said workpiece slide to move in its guide way on the drum, a gear drive operatively connected with a gear of said train of gears and with said pump for driving the latter, said gear being arranged between said set of change speed gears and said driven shaft carried by the workpiece slide.

' 5. In a gear grinding machine as claimed in claim 2, a hydraulic motor drivingly connected with the rotatable casing of said differential gearing, the connection of said hydraulic motor with said rotatable casing being such that during the working movement of the workpiece slide and also during the idle return movement of said workpiece slide any play in the differential gear train is eliminated.

6. In a gear grinding machine of the character described, a base, a slide provided with means thereon for rotatably supporting a toothed workpiece for a grinding operation, said means including a driven shaft carried by said slide in axial alinement with the workpiece when mounted on said slide and adapted to rotate said workpiece, a drum rotatably adjustably mounted on said 15 base about a horizontal axis, a guide way on one end face of said drum in which said slide is mounted for reciprocative movement, a first synchronous motor secured to said drum and having its armature shaft arranged at right angles with respect to the axis of rotation of said drum, a train of spur gears between said armature shaft and said driven shaft carried by the slide, the

. axes of all of the spur gears in said train of gears being parallel to each other, a grinding wheel, a horizontal guide way on said base, a slide on which said grinding wheel is mounted movable in said horizontal guide way toward and away from the end face of said drum on which said workpiece supporting slide is mounted, a second synchronous motor on said grinding wheel slide for operating the grinding wheel, means to reciprocate said grinding wheel slide and for causing the grinding wheel to engage the workpiece on the workpiece slide only during the movement of the latter in one direction, means to withdraw the grinding wheel slide from the workpiece slide a predetermined distance in advance of the beginning of the movement of the latter in the opposite direction and to bring the grinding wheel again into its operative position prior to the start of the workpiece slide in the first named direction which is the working stroke, and means for effecting the return movement of the workpiece slide at a higher speed.

"I. In a gear grinding machine as claimed in claim 2, including a set of change speed gears arranged in the gear means operated by the workpiece slide for rotating the casing of said diflerential gearing, and clamping means adapted to arrest and lock said casing against rotation when grinding a workpiece having straight teeth.

8. In a gear grinding machine as claimed in claim 2, including a set of change speed gears arranged in the gear means operated by the workpiece slide for rotating the casing of said differential gearing, and clamping means adapted to arrest and lock said casing against rotation when grinding a workpiece having straight teeth, means to maintain the clamping pressure at a predermined limit comprising a hydraulic motor adapted to operate under variable pressure, and means to prevent the variable pressure between the teeth of the differential gears produced by the varying ratios of the said set of change speed gear to exceed predetermined limits.

9. In a gear grinding machine of the character described, a base, a slide provided with means thereon for rotatably supporting a toothed workpiece for a grinding operation, said means including a driven shaft carried by said slide in axial alinement with the workpiece when mounted on said slide and adapted to rotate said workpiece, a drum rotatably adjustably mounted on said base about a horizontal axis, a guide -way on one end face of said drum in which said slide is mounted for reciprocative movement, a first synchronous motor lecured to said drum and having its armature shaft arranged at right angles with respect to the axis of rotation of said drum, a train of spur gears between said armature shaft and said driven shaft carried by the slide, the axes of all of the spur gears in said train of gears being parallel to each other, a grinding wheel, a horizontal guide way on said base, a slide on which said grinding wheel is mounted movable in said horizontal guide way toward and away from the end face of said drum on which said workpiece supporting slide is mounted, a second synchronous motor on said grinding wheel slide for operating slide only during the movement of the latter in one direction and having means for withdrawing the grinding wheel slide from the workpiece slide a predetermined distance in adyance of the beginning of the movement of the latter in the opposite direction and mean ffor bringing the grinding wheel again in operative position prior to the start of the workpiece slide in the first named working stroke direction, and hydraulic controlling means for effecting the return movement of the grinding wheel slide during the idle return movement of the workpiece slide independ ent of said manually operable infeed device and of said automatic infeed device.

10. In a gear grinding machine as claimed in claim 1, including in said hydraulically operable means a valve,a hydraulic cylinder on said workpiece slide and controlled by said valve, electromagnets adapted to operate said valve, 9. reversing switch in circuit with said electro-magnets.

means on said workpiece slide for actuating said reversing switch when the workpiece slide reaches the ends of its respective strokes for energizing said electro-magnets one at a timet thereby causing an adjustment of said valve to reverse the flow of pressure fluid in said hydraulic cylinder, and a manually operable switch for energizing said electro-magnets independently of said workpiece slide.

1l, In a gear grinding machine as claimed in claim 1, means to reciprocate said grinding wheel slide and for causing the grinding wheel to engage the workpiece on the workpiece slide only during the movement of the latter in one direction, means to withdraw the grinding wheel slide from the workpiece slide a predetermined distance in advance of the beginning of the movement of the latter in the opposite direction and to bring the grinding wheel again into its operative position prior to the start of the workpiece slide in the first named direction which is the working stroke, and an automatic damping device opcratively connectedwith said hydraulically operable means for reducing the speed of the infeed movement of the grinding wheel slide short- 15; before the grinding wheel engages the workp ece.

12. In a gear grinding machine of the character described, a base, a slide provided with means thereon for rotatably supporting a toothed workpiece for a grinding operation, said means including a driven shaft carried by said slide in axial allnement with the workpiece when mounted on said slide and adapted to rotate said workpiece, a drum rotatably adiustably mounted on said base, a guide way on one end face of said drum in which said slide is mounted for reciprocative movement, a first synchronous motor secured to said drum and having its armature shaft arranged at right angles with respect to the axis 17 18 chronous motor on said grinding wheel slide for operating the grinding wheel, and hydraulically UNITED STATES PATENTS operable means for adjusting the relative posi- Number Name D tion of the grinding wheel slide with respect to 1 773 677 Herrman 61930 the workpiece slide and for causing the work- 5 2307238 Ross Jan 1943 piece slide "to move in its guide way on said drum. 3 Olson Sept: 1927 ALFRED RICKENMANN. 1,773,386 Burgess Aug. 19, 1930 FOREIGN PATENTS REFERENCES CITED 10 Number Country Date The following references are of record in the 690,933 France Sept. 27, 1930 file of this patent: 508,744 Great Britain July 5, 1939 

